In the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) system, uplink power control (called as power control for short) is used to control transmitted power of an uplink physical channel, to compensate path loss and shadow of the channel and suppress interference between cells. Wherein, the uplink physical channel controlled by the uplink power control includes Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH) and Sounding Reference Signal (SRS). The LTE uplink power control uses a control mode of combining an open loop with a closed loop.
In the LTE system, the transmitted power of the PUCCH of a User Equipment (UE) on a subframe i is defined as:PPUCCH(i)=min{PCMAX, P0—PUCCH+PL+h(nCQI, nHARQ)+ΔF—PUCCH(F)+g(i)}[dBm]
wherein,
PCMAX is the Configured Maximum UE output power configured by the UE, and the value range of PCMAX is co-determined by multiple parameters, which include: the maximum UE power determined by the UE power class, the maximum configuration power of the system configuration (IE P-Max), the maximum configuration output power offset (PCMAX tolerance), Maximum Power Reduction (MPR) and Additional Maximum Power Reduction (A-MPR) and so on;
P′PUCCH(i)=P0—PUCCH+PL+h(nCQI,nHARQ)+ΔF—PUCCH(F)+g(i) is the transmitted power of the PUCCH estimated by the UE according to open loop power control commands and closed loop power control commands of a base station, path loss estimation, and PUCCH formats scheduled on the subframe i;
PO—PUCCH is an open loop power control parameter, and is a sum of a cell-specific quantity PO—NOMINAL—PUCCH and a UE-specific quantity PO—UE—PUCCH;
ΔF—PUCCH(F) is a power offset related to a PUCCH format(F) and configured by the upper level;
h(n) is a value based on the PUCCH format(F), wherein, nCQI is the number of information bits of Channel Quality Indicator (CQI), and nHARQ is the number of bits of Hybrid Automatic Repeat Request (HARQ);
g(i) is a current power control adjustment state of the PUCCH, which is shown in the following formula:
      g    ⁡          (      i      )        =            g      ⁡              (                  i          -          1                )              +                  ∑                  m          =          0                          M          -          1                    ⁢                          ⁢                        δ          PUCCH                ⁡                  (                      i            -                          k              m                                )                    
wherein, in a Frequency Division Duplex (FDD) system, there are M=1, k0=4. That is, in the FDD system, a power control adjustment state g(i) of the PUCCH on the subframe i (i.e. the current power control adjustment state) is an accumulated value of a power control adjustment state g(i−1) on the subframe i−1 and a Transmitted power Control (TPC) command δPUCCH indicated by the base station on the subframe i−4.
In a Time Division Duplex (TDD) system, values of M and km are related to Uplink and downlink configurations. That is, in the TDD system, the power control adjustment state g(i) of the PUCCH on the subframe i (i.e. the current power control adjustment state) is an accumulated value of the power control adjustment state g(i−1) on the subframe i−1 and a sum of multiple transmitted power control commands PUCCH indicated by the base station on subframes i−k0, i−k1, . . . , i−kM−1.
In the TDD system, when the subframe i is a downlink frame, there is g(i)=g(i−1). The transmitted power control command δPUCCH is a UE-specific closed loop correction value and sent by the base station to a destination UE through a Physical Downlink Control Channel (PDCCH).
The physical downlink control channel bears Downlink Control Information (DCI), which includes downlink or uplink scheduling information and an uplink transmitted power control command and so on. According to different downlink control information, the LTE system defines various downlink control information formats (DCI formats). The transmitted power control commands of the PUCCH are contained in DCI format 1A/1B/1D/1/2A/2 and DCI format 3/3A, each TPC command is of 1 bit or 2 bits and indicates a value of δPUCCH, and a mapping relationship between the TPC command and δPUCCH is shown in tables 1 and 2.
TABLE 1the mapping relationship between the TPC Command andδPUCCH in DCI format 1A/1B/1D/1/2A/2/3TPC Command Field in DCI format 1A/1B/1D/1/2A/2/3δPUCCH [dB]0−1102133
TABLE 2the mapping relationship between the TPC commandand in DCI format 3AδPUCCHTPC Command Field in DCI format 3A[dB]0−111
Wherein, DCI format 3/3A contain the TPC commands of multiple UEs, formats of DCI format 3/3A are as shown in table 1, and after receiving the DCI format 3/3A of the PDCCH, different UEs find out their own TPC commands in corresponding positions therein according to a parameter, namely “a transmitted power control index tpc-Index”, configured by the upper level. For the DCI format 3, the values of the transmitted power control index tpc-Index are the integers within the range of [1,15]; and for the DCI format 3A, the values of the transmitted power control indexes tpc-Index are the integers within the range of [1,31].
DCI formats 1A/1B/1D/1/2A/2 only contain one TPC command aiming at the destination UE thereof The TPC command is precisely the transmitted power control command of the PUCCH corresponding to a Physical Downlink Shared Channel (PDSCH) scheduled by the DCI format.
If the UE does not detect any TPC command on a certain subframe, then δPUCCH=0 dB.
The Physical Uplink Control Channel (PUCCH) bears Uplink Control Information (UCI), which includes Scheduling Request (SR), response information (ACK/NACK) of the Physical Downlink Shared Channel (PDSCH), and feedback quantity/Precoding Matrix Indicator (PMI)/Rank Indication (RI) related to the CQI.
In the LTE system, a resource index of the PUCCH for sending the response information ACK/NACK of one or more PDSCHs is mapped implicitly by a Control Channel Element (CCE) index of the PDCCH which schedules the PDSCH, or is configured by an upper level signaling.
In a LTE-Advanced system (called LTE-A system for short) is the next generation advanced system of the LTE system. As shown in FIG. 2, the LTE-A system adopts a carrier aggregation technique to expand transmission bandwidth, and each aggregated carrier is called as one component carrier (CC). Multiple component carriers can be either successive or not successive, and can be located at either the same operating band or different operating bands.
In the LTE-A system, the user equipment can send multiple Physical Downlink Shared Channels (PDSCH) simultaneously on multiple (downlink) component carriers. The response information ACK/NACK of multiple PDSCHs can be sent by multiple Physical Uplink Control Channels (PUCCH) on one user equipment-specific (uplink) component carrier, or sent by one PUCCH on one user equipment-specific (uplink) component carrier. When the response information, namely Acknowledge/Non-acknowledge (ACK/NACK), of the PDSCHs on multiple component carriers is sent on one PUCCH by the way of ACK/NACK bundling or ACK/NACK multiplexing, how the user equipment determines the current power control adjustment state of the PUCCH and then determines the transmitted power of the PUCCH according to the transmitted power control commands indicated by the base station becomes a problem required to be solved urgently.